Every other free tool on this site works from a public link alone. Discord servers don't expose enough information through an invite link by itself for delivery to happen, which is exactly why the bot at nowon.tools has to be added before you submit anything here. Skip that step, and the system has no way to actually reach your server, even though the order itself will still process and show as delivered.
That last part trips people up more than anything else on this page. An invalid setup doesn't throw an error, it just completes without members showing up, since there's no way for the system to flag a server it can't properly reach. Add the bot first, then submit.